In general, magnesium metal is not used as uncoated material on account of its corrosion characteristic. This work was done by preparing 99.99% pure magnesium coating films by RF magnetron sputtering onto SPCC substrates . The individual preparation conditions of gas pressures and bias voltages were 1×10-2 ~ 1×10-3 Torr and 0V ~ -300V, respectively. The analysis about crystal orientation, morphology and electrochemical characteristic of Mg thin films was performed by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), electrochemical impedance spectroscopy (EIS) etc.. It is as a results of experiment that the morphology of the sputtered films changed from a columnar structure to a granular structure when Ar gas pressure increased or bias voltage decreased. Also, the prepared Mg thin film’s morphology did not have defects and pinholes, and the corrosion resistance was improved by the formation of a homogeneous passive layer.